31e889098a
Impact: allow archs more flexibility on dynamic ftrace implementations
Dynamic ftrace has largly been developed on x86. Since x86 does not
have the same limitations as other architectures, the ftrace interaction
between the generic code and the architecture specific code was not
flexible enough to handle some of the issues that other architectures
have.
Most notably, module trampolines. Due to the limited branch distance
that archs make in calling kernel core code from modules, the module
load code must create a trampoline to jump to what will make the
larger jump into core kernel code.
The problem arises when this happens to a call to mcount. Ftrace checks
all code before modifying it and makes sure the current code is what
it expects. Right now, there is not enough information to handle modifying
module trampolines.
This patch changes the API between generic dynamic ftrace code and
the arch dependent code. There is now two functions for modifying code:
ftrace_make_nop(mod, rec, addr) - convert the code at rec->ip into
a nop, where the original text is calling addr. (mod is the
module struct if called by module init)
ftrace_make_caller(rec, addr) - convert the code rec->ip that should
be a nop into a caller to addr.
The record "rec" now has a new field called "arch" where the architecture
can add any special attributes to each call site record.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
57 lines
1.2 KiB
C
57 lines
1.2 KiB
C
#ifndef _ASM_X86_FTRACE_H
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#define _ASM_X86_FTRACE_H
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#ifdef CONFIG_FUNCTION_TRACER
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#define MCOUNT_ADDR ((long)(mcount))
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#define MCOUNT_INSN_SIZE 5 /* sizeof mcount call */
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#ifndef __ASSEMBLY__
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extern void mcount(void);
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static inline unsigned long ftrace_call_adjust(unsigned long addr)
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{
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/*
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* call mcount is "e8 <4 byte offset>"
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* The addr points to the 4 byte offset and the caller of this
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* function wants the pointer to e8. Simply subtract one.
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*/
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return addr - 1;
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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struct dyn_arch_ftrace {
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/* No extra data needed for x86 */
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};
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_FUNCTION_TRACER */
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#ifdef CONFIG_FUNCTION_RET_TRACER
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#define FTRACE_RET_STACK_SIZE 20
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#ifndef __ASSEMBLY__
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/*
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* Stack of return addresses for functions
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* of a thread.
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* Used in struct thread_info
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*/
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struct ftrace_ret_stack {
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unsigned long ret;
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unsigned long func;
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unsigned long long calltime;
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};
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/*
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* Primary handler of a function return.
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* It relays on ftrace_return_to_handler.
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* Defined in entry32.S
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*/
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extern void return_to_handler(void);
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#endif /* __ASSEMBLY__ */
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#endif /* CONFIG_FUNCTION_RET_TRACER */
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#endif /* _ASM_X86_FTRACE_H */
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